Delivery pump

ABSTRACT

In a feed pump ( 2 ), guide vanes ( 9 ) fastened on a driven impeller ( 7 ) project into a recess ( 11 ) of a molding ( 8 ) annularly surrounding the impeller ( 7 ). The guide vanes ( 9 ) are located with a slight clearance opposite the wall of the recess ( 11 ). The guide vanes ( 9 ) can thereby have a particularly large surface. Moreover, a depositing of dirt in the radially outer region of the impeller ( 7 ) is avoided.

BACKGROUND OF THE INVENTION

The invention relates to a feed pump, in particular a fuel pump, with adriven impeller rotating between two casing parts and carrying guidevanes delimiting at least one ring of vane chambers, with a part-annularchannel arranged in the region of the vane chambers in the casing partsand extending from an inlet duct to an outlet duct, and with a fixedmolding arranged on the outer circumference of the impeller, the moldinghaving a recess adjacent to the part-annular channel.

Such a feed pump, designed as a peripheral pump, is known, for example,from DE 43 33 204 C2. In this feed pump, guide vanes arranged on bothsides of the impeller are arranged on the outer circumference. Themolding has a radially inward-pointing edge axially delimiting tworecesses. This edge is located opposite the outer boundaries of guidevanes. DE 196 07 573 A1 discloses a feed pump, in which one edge of theimpeller and one edge of the molding are located opposite one another.

These feed pumps have the disadvantage that the guide vanes have only avery small configuration in relation to the total cross-sectional areaof the part-annular channel, of the recess and of the vane chambers. Asa result, only a very low momentum can be transmitted to the flow to beconveyed. The feed pumps consequently have particularly low efficiency.

The problem on which the invention is based is to configure a feed pumpof the type initially mentioned, in such a way that it has particularlyhigh efficiency.

BRIEF DESCRIPTION OF THE INVENTION

This problem is solved, according to the invention, in that the guidevanes project into the recess of the molding and are located with aslight clearance opposite the wall of the recess.

By virtue of this configuration, the vane chambers are arrangedpartially in the region of the molding. As a result, the guide vanes canextend over all the regions located outside the part-annular channel.The guide vanes therefore have a particularly large area and, moreover,are arranged particularly far on the outside in the radial direction.The feed pump according to the invention consequently has particularlyhigh efficiency. As compared with a side channel pump, in which the vanechambers are arranged completely in one end face of the impeller, thefeed pump according to the invention has the advantage of beingparticularly insensitive to contamination of the medium to be conveyed,since, in the radially outer region of the impeller, there are no planesurfaces of the impeller and of the pump casing which are locatedopposite one another and between which dirt may accumulate. This leads,particularly in the case of the feed pump used as a fuel pump, toparticularly low susceptibility to wear. The molding may be designed asa spacer spacing the casing parts from one another.

In the case of two rings of guide vanes arranged in each case in one endface of the impeller, the feed pump according to the invention hasparticularly high efficiency when the molding has two recesses delimitedby a radially inward-pointing edge and when guide vanes arranged on endfaces located opposite one another are located with a slight clearanceopposite the axial boundaries of the edge.

According to another advantageous development of the invention,turbulences of the medium to be conveyed, in the region of the recess,can be kept particularly low when the guide vanes have an arcuateconfiguration in their region projecting into the recess. Preferably,the guide vanes have essentially a semicircular shape in a radialsection through the impeller.

According to another advantageous development of the invention, dirtadhering to surfaces of the molding or of the casing parts can beavoided particularly reliably when the guide vanes project beyond anouter edge of the impeller by at least half their height.

The feed pump according to the invention can be configured selectivelyfor a separation or an axial throughflow of vane chambers locatedopposite one another when the outer edge of the impeller and theradially inward-pointing edge of the molding are located with anintended clearance opposite one another.

The assembly of the feed pump according to the invention becomesparticularly simple when the molding has at least two ring elements.

According to another advantageous development of the invention, themolding can have a closed ring shape and therefore be produced andassembled particularly cost-effectively when the impeller has atwo-layer configuration.

Wear leading to a lowering of the efficiency of the feed pump accordingto the invention can be avoided in a simple way when the molding ismanufactured from a harder material than the impeller.

The feed pump according to the invention has particularly high stabilitywhen, in the case of an impeller manufactured from plastic, the moldinghas in the region of the recess a wall made from metal or ceramic.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention permits numerous embodiments. In order to make its basicprinciple even clearer, two of these are illustrated in the drawing andare described below. In the drawing

FIG. 1 shows a sectional illustration through a feed pump according tothe invention,

FIG. 2 shows a sectional illustration through the feed pump from FIG. 1along the line II—II,

FIG. 3 shows a greatly enlarged sectional illustration through the feedpump from FIG. 2 along the line III—III,

FIG. 4 shows a greatly enlarged sectional illustration of a furtherembodiment of the feed pump in the region of a feed chamber.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a feed pump 2 driven by an electric motor 1, for examplefor the conveyance of fuel in a present-day motor vehicle. The feed pump2 has an impeller 7 driven between two casing parts 3, 4 of a pumpcasing 5 and fastened on a shaft 6 of the electric motor 1. The casingparts 3, 4 are held with a clearance by means of an annular molding 8.The impeller 7 has, on each of its end faces, a ring of vane chambers 10delimited by guide vanes 9. The guide vanes 9 in this case projectbeyond the edge of the impeller 7 and penetrate into peripheral recesses111 of the molding 8. Between the recesses 11, the molding 8 has an edge12 projecting radially inward between guide vanes 9 opposite oneanother. Part-annular channels 13 are arranged in those regions of thecasing parts 3, 4 which are located opposite the vane chambers 10. Thevane chambers 10 and the part-annular channels 13 form feed chambers 16extending from an inlet duct 14 to an outlet duct 15 of the feed pump 2.The inlet duct 14 and the outlet duct 15 in each case have an overflowduct 17, 18 arranged in the molding 8 and led past the impeller 7. Whenthe impeller 7 is driven by the electric motor 1, the medium to beconveyed is sucked through the inlet duct 14 and is led to the outletduct 15 via the feed chambers 16. Circulation flows are formed in eachcase within the feed chambers 16. For the sake of clarity, the flows ofthe conveyed medium are marked by arrows in the drawing.

The inlet duct 14 and the outlet duct 15 are illustrated in FIG. 1 asbeing rotated into the sectional plane. As FIG. 2 shows in a sectionalillustration through the feed pump 2 from FIG. 1 along the line II—II,the part-annular channels 13 extend over an angular range ofapproximately 300°. The guide vanes 9 extend, in each case over halftheir height, in the impeller 7 and in the recess 11 of the molding 8.The molding 8 is composed of two ring elements 19, 20.

FIG. 3 shows, greatly enlarged, a part region of the feed pump 2 fromFIG. 2 in a sectional illustration along the line III—III. It can beseen, here, that the guide vanes 9 have an approximately semicircularconfiguration. The recesses 11 of the molding 8 have an arcuate contourcorresponding to the region of the guide vanes 9 which projects beyondthe impeller 7. In this case, those regions of the guide vanes 9 whichproject into the recesses 11 of the molding 8 are located with a slightclearance opposite the wall of said molding. As a result, a part regionof the vane chambers 10 is arranged within the molding 8. The radiallyinward-pointing edge 12 of the molding 8 is located with slightclearance opposite a radially outward-pointing edge 21 of the impeller7.

FIG. 4 shows a part section through a radially outer region of a furtherembodiment of the feed pump 2 from FIG. 1. This embodiment differs fromthat of FIG. 3, above all, in that an impeller 24 rotating between twocasing parts 22, 23 has a two-layer configuration. As a result, amolding 25 holding the casing parts with a clearance can be configuredannularly in one piece. A radially inward-pointing edge 26 of themolding 25 has a clearance in relation to a radially outward-pointingedge 27 of the impeller 24. The medium to be conveyed can thereby flowfrom one feed chamber 28 over into the other feed chamber 29. Overflowducts 17, 18 illustrated in FIG. 1 are therefore unnecessary. As in theembodiment illustrated in FIG. 3, guide vanes 30 fastened on theimpeller 24 project into recesses 31 of the molding 25 and are locatedwith a slight clearance opposite the wall of the latter.

1. A feed pump in particular a fuel pump, with a driven impeller (7, 24)rotating between two casing parts and carrying guide vanes delimiting atleast one ring of vane chambers, with a part-annular channel arranged inthe region of the vane chambers in the casing parts and extending froman inlet duct to an outlet duct, and with a fixed molding manufacturedfrom a harder material than the impeller (7, 24) arranged on the outercircumference of the impeller, the molding having a recess adjacent tothe part-annular channel, characterized in that the guide vanes (9, 30)project into the recess (11, 31) of the molding (8, 25) and are locatedwith a slight clearance opposite the wall of the recess (11, 31).
 2. Afeed pump having a driven impeller manufactured from plastic, rotatingbetween two casing parts and carrying guide vanes delimiting at leastone ring of vane chambers, with a part annular channel arranged in theregion of the vane chambers in the casing parts and extending from aninlet duct to an outlet duct and with a fixed molding arranged on theouter circumference of the impeller, the molding having a recess and inthe region of the recess a wall made from metal or ceramic.
 3. The feedpump as claimed in claim 1 or 2, characterized in that the molding (8,25) has two recesses (11, 31) delimited by a radially inward-pointingedge (12, 26) and in that guide vanes (9, 30) arranged on end faceslocated opposite one another are located with a slight clearanceopposite the axial boundaries of the edge (12, 26).